Method for the production of 2,6-dichloro-5-fluoronicotinonitrile and the chemical compound 3-cyano-2-hydroxy-5-fluoropyride-6-one-monosodium salt its tautomers
申请人:Bayer Aktiengesellschaft
公开号:US06197964B1
公开(公告)日:2001-03-06
The process according to the invention can be illustrated by way of example by the following equation:
The monosodium salt of the 3-cyano-2-hydroxy-5-fluoropyrid-6-one (cf. Formula (I)) and/or tautomers thereof are preferably employed in the process according to the invention.
The use of a basic catalyst enables significantly lower amounts of chlorinating agent to be employed in the chlorination according to the invention than is necessary, for example, for chlorination of the free dihydroxy compound according to EP-A 333 020. Furthermore, the product 2,6-dichloro-5-fluoronicotinonitrile is obtained in a high purity and high yields after hydrolysis, which is not the case if the conditions according to EP-A 333 020 are applied.
Basic catalysts which can be used for the process according to the invention are, for example, organic bases, for example aliphatic and aromatic amines and amides, and also inorganic bases, for example basic compounds of nitrogen and phosphorus and salts thereof. Preferred basic catalysts are: pyridine, pyridines alkylated with 1 to 3 C1-C6-alkyl groups, piperidine, piperidines, imidazoles and indoles alkylated with 1 to 3 C1-C6-alkyl groups, N—C1-C6-alkylaminopyridines, N—di-C1-C6-alkylated anilines, tertiary N—C1-C6-alkylamines, urea and urea derivatives. Particularly preferred basic catalysts are triethylamine, urea and ethylpiperidine.
本发明的过程可以通过以下方程式举例说明:首选采用3-氰基-2-羟基-5-氟吡啶-6-酮(参见公式(I))的单钠盐和/或其互变异构体来进行本发明的过程。使用碱性催化剂可以使氯化过程中所需的氯化剂量显著降低,例如相对于根据EP-A 333 020中自由二羟基化合物的氯化所需的氯化剂量。此外,在水解后,产物2,6-二氯-5-氟尼古丁腈可以高纯度地和高收率地得到,而如果应用EP-A 333 020中的条件则不是这种情况。可用于本发明的碱性催化剂包括有机碱,例如脂肪族和芳香族胺和酰胺,以及无机碱,例如氮和磷的碱性化合物及其盐。首选的碱性催化剂包括:吡啶,1至3个C1-C6烷基取代的吡啶,哌啶,1至3个C1-C6烷基取代的哌啶,咪唑和1至3个C1-C6烷基取代的吲哚,N-C1-C6-烷基氨基吡啶,N-二C1-C6-烷基化苯胺,三级N-C1-C6-烷基胺,尿素和尿素衍生物。特别优选的碱性催化剂包括三乙胺,尿素和乙基哌啶。